The present invention relates to a color filter manufacturing method and apparatus for manufacturing a color filter by discharging inks onto a substrate using ink-jet heads and coloring each pixel of the color filter, a color filter, a color filter substrate, a display device, and an apparatus having the display device.
In general, liquid crystal display devices are mounted in personal computers, wordprocessors, pinball machines, car navigation systems, compact TV sets, and the like. There have been great demands for liquid crystal display devices. However, liquid crystal display devices are expensive, and hence the demand for a reduction in cost has become increasingly higher.
A color filter as a component of a liquid crystal display device is formed by arranging pixels such as red (R), green (G), and blur (B) pixels on a transparent substrate. A black matrix for blocking light is arranged around each pixel to improve the display contrast.
The colored pixel portion of a color filter is formed by a dyeing method, a pigment dispersion method, an electrodeposition method, or the like.
In order to meet the demand for a reduction in the cost of a color filter, a method of forming pixels by a printing or ink-jet method has been proposed. In the printing method, however, since a colored pixel portion is formed by repeating a transfer (from a printing plate)/drying process three times for R, G, and B pixels, the yield decreases.
In the ink-jet method, as disclosed in, e.g., Japanese Patent Laid-Open No. 59-75205, coloring solutions containing coloring materials of three colors, i.e., R, G, and B, are sprayed on a transparent substrate by an ink-jet system, and the respective coloring solutions are dried to form colored image portions. In such an ink-jet system, R, G, and B pixels can be formed at once, allowing great simplification of the manufacturing process and a great reduction in cost.
In the ink-jet system, however, a head may become incapable of discharging an ink accidentally or because of scorching of an ink. In this case, the normal production process must be restored by, for example, quickly replacing or cleaning the head. In this case, all resultant defective substrates must be discarded, or part of the defective substrate must be discarded if the substrate is a multi-filter substrate.
Recently, for efficient production, larger substrates have been popular, e.g., 10-inch two-, four, and six-filter substrates including 300 mm.times.200 mm, 360 mm.times.460 mm, and 550 mm.times.650 mm substrates. For this reason, even if head abnormality detection is performed before a coloring operation, when an abnormality such as an ink discharge failure occurs in the first filter, all the five remaining filters become defective products. The manufacture of such defective color filters causes a decrease in yield. Consequently, the cost merit in the ink-jet method is canceled out.
When a head is started to discharge an ink after a certain idle time, the amount of ink discharged is unstable immediately after the discharging operation, although the head may not become incapable of discharging the ink. If a high-resolution pattern for a color filter or the like is colored by using such a head, color mixing may be caused between adjacent pixels because of an excessively large amount of ink discharged, or a desired pixel may not be colored to cause a white omission because of an excessively small amount of ink discharged.